Filters of the type used for filtering particulate matter from engine intake air sometimes include one or more layers of a porous filter material that is formed into a convoluted pattern, often referred to in the industry as fluted filter media. The fluted filter media sometimes also includes one or more additional layers of non-corrugated material attached to the convoluted filter material. These additional sheets are known by various names, such as face sheets, or backing sheets, and may be formed from either porous or non-porous material.
In one commonly used form of filter element, a length of the fluted filter media is wound about an axis into a coiled shape to form a media pack having one axial end adapted for receiving a flow of fluid and the other axial end adapted for discharging the fluid after it is filtered by the fluted filter media forming the media pack. After formation of the coiled media pack, secondary operations may be performed, to add seals or mounting provisions to the media pack, to form a filter element that can be inserted into a filter housing that directs a flow of fluid through the filter element.
As part of the process of forming a coiled filter pack for a filter element, a number of operations must typically be performed, such as trimming the fluted filter media to form a leading edge of the media, attaching the leading edge to a mandrel used for winding the coiled filter pack, feeding a predetermined length of the media to the mandrel during winding, trimming the media a second time to form a trailing edge of the media, securing the trailing edge to the filter pack, and applying adhesives or sealants to portions of the media as it is wound into a coil. In forming the leading and trailing edges, it is desirable to trim the media directly through a peak of the convolutions forming the fluted media, to thereby form a half-peak at the leading and trailing edges that can be filled with an adhesive or sealant. It is also desirable to control the tension on the media during winding to ensure that the flutes of the underlying layers are not crushed in the process of winding the subsequent layers, and to provide uniformity in the final shape and size of the coiled media pack.
Because the filter element incorporating the media pack is generally disposable, and because there are typically multiple sources from whom a consumer may purchase replacement filter elements, it is desirable to automate the process of winding the media pack, so that the manufacturing cost and selling price of the filter element can be minimized. Prior approaches to automating the process of winding such media packs have not been entirely satisfactory, however, particularly where the media pack has a cross-section that is other than round, such as square, rectangular, oval, or race-track shaped with a rectangular central section joining rounded ends.
In general, prior approaches have relied upon undesirably complex conveyor mechanisms and machinery for performing some of the required operations, and have not been capable of providing many of the desired operations in an automated form. As a result, some operations, such as trimming the media to length have had to be performed by hand, which heretofore precluded fully taking advantage of manufacturing opportunities such as feeding the media from a large master roll of the media. Prior approaches have also not allowed for adequate control of the tension in the media during winding.
It is desirable, therefore, to provide an improved apparatus and method for forming a filter media pack by winding a fluted filter media into a coil.